GND

V

DD

PenTouch

X+

Y+

Y-

HighwhentheX+orY+

driverison,orwhenany

sensorconnection/short-

circuittestsareactivated.

GND

ON

Sense

Viasgotosystemanaloggroundplane.

GND

Highwhen

theX+orY+

driverison.

Control

Logic

R

IRQ

VDD/REF

PENIRQ

Connectto

AnalogSupply

Preprocessing

7Acquired

Data

7

7m asu

e

rementsinput

intotemporaryarray

Sortby

descendingorder

7

Averagingoutp t

u

fromwindowof3

3

TSC2008

Figure 27. Example of a Pen-Touch Induced Interrupt via the PENIRQ Pin

The TSC2008 has a fixed combined MAV filter (median value filter and averaging filter).

MAV Filter

If the acquired signal source is noisy because of the digital switching circuit, it may necessary to evaluate the

data without noise. In this case, the median value filter operation helps remove the noise. The array of seven

converted results is sorted first. The middle three values are then averaged to produce the output value of the

MAV filter.

The MAV filter is applied to all measurements for all analog inputs including the touch screen inputs, temperature

measurements TEMP1 and TEMP2, and auxiliary input AUX. To shorten the conversion time, the MAV filter may

be bypassed though the setup command; see Table 2 and Table 4.

Figure 28. MAV Filter Operation (Patent Pending)

18

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Product Folder Link(s): TSC2008